Granulocyte-Colony Stimulating Factor (G-CSF) and Granulocyte-Macrophage CSF (GM-CSF) Administration Enriches for Highly Suppressive CD4+CD45RA-Foxp3hi Cells in Leukapheresis Products of Rhesus Monkeys

Granulocyte-Colony Stimulating Factor (G-CSF) and Granulocyte-Macrophage CSF (GM-CSF) Administration Enriches for Highly Suppressive CD4⁺CD45RA^–Foxp3^hi Cells in Leukapheresis Products of Rhesus Monkeys

K. Sasaki, Y. Wang, L. Lu, J. Hughes, V. Vujevich, A. W. Thomson, M. B. Ezzelarab

Starzl Transplantation Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA

Meeting: 2020 American Transplant Congress

Abstract number: C-375

Keywords: Immunosuppression, Primates, T cells, Tolerance

Session Information

Session Name: Poster Session C: Immunosuppression Preclinical Studies

Session Type: Poster Session

Date: Saturday, May 30, 2020

Session Time: 3:15pm-4:00pm

Presentation Time: 3:30pm-4:00pm

Location: Virtual

*Purpose: In humans, CD4⁺CD45RA^–Foxp3^hi T cells comprise a regulatory T cell (Treg) subset with highly suppressive function. We have previously shown that granulocyte-colony stimulating factor (G-CSF) and granulocyte-macrophage CSF (GM-CSF) administration enhances the incidence of peripheral blood CD4⁺CD25^hiFoxp3^hi Treg in non-human primates. Here, we examined whether GM-CSF/G-CSF administration enhances the incidence of CD4⁺CD45RA^–Foxp3^hi Treg in leukapheresis products (LP) of rhesus monkeys.

*Methods: Rhesus monkeys (n=6; 5-7kg) were treated sequentially with recombinant human GM-CSF (10 mg/kg/day for 4 days), then recombinant human G-CSF (10 mg/kg/day for 4 days), followed by leukapheresis. Treg in peripheral blood mononuclear cells (PBMC), obtained before treatment, and in LP obtained after GM-CSF/G-CSF administration were assessed based on their expression of CD45RA, CD25 and Foxp3. The percentages and phenotype of CD4⁺CD45RA^–Foxp3^hi Treg and CD4⁺CD45RA^–Foxp3^lo populations were evaluated. Additionally, LP CD4⁺CD45RA^–CD25^lo and CD4⁺CD45RA^–CD25^hi populations were flow-sorted and assessed for their suppressive function.

*Results: After G-CSF/GM-CSF administration, the incidence of CD4⁺CD45RA^–Foxp3^hi Treg increased significantly in LP (p<0.01), compared to peripheral blood before treatment. Furthermore, the ratio of CD4⁺CD45RA^–Foxp3^hi to CD4⁺CD45RA^–Foxp3^lo cells also increased significantly (p<0.05). In LP, The CD4⁺CD45RA^–CD25^hi population expressed significantly higher levels of Foxp3, CTLA4 and Helios, compared to the CD4⁺CD45RA^–CD25^lo population (p<0.05). In 3 animals, LP flow-sorted CD4⁺CD45RA^–CD25^hi cells exhibited superior suppression of T cell proliferation in response to anti-CD2/CD3/CD28 stimulation, compared to the CD4⁺CD45RA^–CD25^hi population.

*Conclusions: G-CSF/GM-CSF administration enhances the incidences of highly suppressive CD4⁺CD45RA^–Foxp3^hi T cells in LP of mobilized rhesus monkeys. These observations further support the therapeutic potential of Treg-enriched LP from mobilized individuals.

To cite this abstract in AMA style:

Sasaki K, Wang Y, Lu L, Hughes J, Vujevich V, Thomson AW, Ezzelarab MB. Granulocyte-Colony Stimulating Factor (G-CSF) and Granulocyte-Macrophage CSF (GM-CSF) Administration Enriches for Highly Suppressive CD4⁺CD45RA^–Foxp3^hi Cells in Leukapheresis Products of Rhesus Monkeys [abstract]. Am J Transplant. 2020; 20 (suppl 3). https://atcmeetingabstracts.com/abstract/granulocyte-colony-stimulating-factor-g-csf-and-granulocyte-macrophage-csf-gm-csf-administration-enriches-for-highly-suppressive-cd4cd45ra-foxp3hi-cells-in-leukapheresis-products-of-rhesus-monkey/. Accessed June 24, 2025.

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